The field of the present invention is internal combustion engine valve driving mechanisms capable of varying timing and lift.
Valve timing and valve lift of intake and exhaust valves in a four cycle internal combustion engine are important factors on which the performance of internal combustion engines depend. Mechanisms have been devised to accomplish variations in valve timing and lift during operation of the engine according to measured states of the engine. Camshaft support devices are known which are pivotally mounted within the engine. A camshaft is then rotatably mounted within the support device and engages appropriate rocker arms. Through a pivoting of the camshaft support device, the cam is moved relative to the rocker arm such that the cam operates on selected portions of the rocker arm surface. Depending on the direction of relative movement between the camshaft support device and the rocker arm, and the configuration of the rocker arm surface, the timing of valve opening and valve closing, and the valve lift may be controlled.
By controlling the profile of valve operation, it is possible to obtain improved intake inertia effects for increased volumetric efficiency. Pulsation effects of the exhaust system may also be utilized for improved performance through valve timing. The volume of fresh air passing through the engine may also be controlled when appropriate as well as the back flow of the exhaust pressure into the intake system.